Joint processing of image plane and wavefront sensor information to measure large aberrations in optical systems

摘要

Abstract: Hartmann sensors and shearing interferometers have dynamic range limitations which bound the strength of the aberration which can be sensed. The largest aberration which can be reliably sensed in a Hartmann sensor must have a local gradient small enough so that the spot formed by each lenslet is confined to the area behind the lenslet - if the local gradient is larger, spots appear under nearby lenslets, causing a form of cross talk between the wave front sensor channels. Similarly, the effectiveness of shearing interferometer-based aberration sensing can be reduced by strong phase gradients which cause unresolved 2$pi phase jumps in the measured fringe pattern. In this paper we describe a wave front reconstruction algorithm which processes the whole image measured by either a Hartmann sensor or a shearing interferometer, and a conventional image formed using the incident aberration. We show that this algorithm can accurately estimate aberrations for cases where the aberration is strong enough to cause many of the images formed by individual Hartmann sensor lenslets to fall outside the local region of the Hartmann sensor detector plane defined by the edges of a lenslet. !11